From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [patch 13/44] mm: restore KERNEL_DS optimisations Date: Tue, 24 Apr 2007 11:43:18 +0100 Message-ID: <20070424104318.GA13268@infradead.org> References: <20070424012346.696840000@suse.de> <20070424013434.155713000@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Linux Filesystems , Mark Fasheh , Linux Memory Management To: Nick Piggin Return-path: Received: from pentafluge.infradead.org ([213.146.154.40]:44529 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932760AbXDXKnZ (ORCPT ); Tue, 24 Apr 2007 06:43:25 -0400 Content-Disposition: inline In-Reply-To: <20070424013434.155713000@suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Apr 24, 2007 at 11:23:59AM +1000, Nick Piggin wrote: > Restore the KERNEL_DS optimisation, especially helpful to the 2copy write > path. > > This may be a pretty questionable gain in most cases, especially after the > legacy 2copy write path is removed, but it doesn't cost much. Well, it gets removed later and sets a bad precedence. Instead of adding hacks we should have proper methods for kernel-space read/writes. Especially as the latter are a lot simpler and most of the magic in this patch series is not needed. I'll start this work once your patch series is in. In general there seems to be a lot of stuff in the earlier patches that just goes away later and doesn't make much sense in the series. Is there a good reason not to simply consolidate out those changes completely?